Thermoforming of polyolefins is well known. Generally, a sheet of the polyolefin is formed or shaped by heating the sheet above the softening temperature of the polyolefin, fitting the sheet along the contours of a mold with pressure supplied by vacuum or other force, and removing the shaped article from the mold after cooling below its softening point.
A common problem heretofore in thermoforming polyolefins is that polyolefins lose much of their gloss during the thermoforming process. Gloss is the geometrically selective reflectance of a surface responsible for its shiny and lustrous appearance. Gloss is an important property in applications in which a shiny or lustrous appearance is desirable, such as, for example, the manufacture of liners in the home appliance industry.
It has been known to employ polymer processing aids in the extrusion of polyolefins. Such processing aids are added to inhibit melt fracture of the polyolefins during extrusion at a high rate of extrusion. Examples of such extrusion processing additives are disclosed in U.S. Pat. Nos. 3,125,547; 3,459,834; 4,334,037; 3,334,157; and 3,005,795. However, extrusion is a dynamic process and as far as applicant is aware, fluoroelastomers have not heretofore been employed in static processes such as thermoforming.